—Naht'n Kingdom, Naht'n Land; Euro Continent
The way Lethe proposed to Olivia is in front of Olivia's parents, kneeling in front of Olivia as he puts the ring on Olivia after their oath.
"My body and soul belong to you," Lethe said.
"My body and soul belong to you as well," Olivia responded.
Lethe then puts the ring on Olivia's ring finger on her left hand, a hand that she barely uses in anything, so the ring will be safe.
"Earning money as an adventurer while training in the academy is worth it, I am able to buy this expensive ring for her," Lethe thought with a smile of relief and satisfaction.
"I can't wait for the wedding," Olivia thought, blushing happily.